1. Field of the Invention
The present invention relates to an image processor incorporated in a display device such as a flat panel display device or a CRT display device, or connected to a display device.
2. Description of the Related Art
It has been required to improve image quality by processing digital image signals, in company with increase, in processing speed of an LSI.
FIG. 8 is a schematic block diagram showing a prior art image display device.
Digital image signals of three primary colors R, G and B are provided to respective image processing circuits 1OR, 1OG and 10B to perform filtering processing such as edge enhancement, and the results thereof are provided through a display control circuit 12 to an LCD panel 14 to display pictures on the panel 14. The display control circuit 12 includes a multi-port VRAM and a control circuit therefor.
However, as shown in FIG. 9, when an edge enhancement processing is followed by clipping in regions where pixels are saturated at the maximum value MAXO or the minimum value no effect of the edge enhancement processing can be achieved.
Accordingly, it is an object of the present invention to provide a image processor capable of effectively performing an image processing such as an edge enhancement processing even in a region of saturated pixel values, with a simple construction.
In one aspect of the present invention, there is provided an image processing circuit comprising: a data zone expansion circuit, receiving input data X, expanding a data zone of the input data by linearly converting X to (xcex1X+xcex2), where xcex1 and xcex2 are given values, providing the data-zone expanded data (xcex1X+xcex2); and an image processing circuit, performing image processing on the data-zone-expanded data (xcex1X+xcex2).
In the prior art, when an edge enhancement processing is applied on image data, an image processing effect such as edge enhancement could not be achieved in pixel value
saturated regions at the maximum or minimum value. Such an effect can be achieved with this aspect having a simple construction that the data zone expansion circuit is provided at the preceding stage of the image processing circuit, thereby contributing to improvement in image quality.
Other aspects, objects, and the advantages of the present invention will become apparent from the following detailed description taken in connection with the accompanying drawings.